This invention is directed generally to monitoring of a flow of discrete small articles, and more particularly to the accurate detection and counting of seeds being planted by a seed planting machine.
More specifically, the present invention is directed to the problem of providing a seed monitoring apparatus capable of providing a substantially accurate count of different types of seeds which may be planted by the same seed planting machine, but requires no action by the operator in the way of modifications or changing of components thereof to accomplish this end.
Seed monitoring and counting apparatus used in the past have generally included a housing or other means forming a path of travel for seeds to traverse on their way to the ground to be planted. Conventionally, a photosensor arrangement is used, consisting of one or more light emitting devices and one or more photo-sensitive elements mounted generally on opposing sides of the path of travel. Consequently, a seed passing along the path of travel will momentarily partially obscure the light falling on one or more of the photo-sensitive elements and thereby cause the emission of a signal therefrom. Suitable circuits are provided to receive these signals and to derive therefrom a pulse signal for driving a visual indicator device such as a flashing lamp or for driving a cumulative counter thereby keeping a running count of the number of seeds planted.
While such devices have been heretofore proposed and have in fact proven highly reliable in operation in monitoring and/or counting seeds of a particular type, it has heretofore been difficult or impossible to provide a single monitoring apparatus capable of monitoring different types or sizes of seeds. In this regard, at least three types of problems are encountered when it is desired to change over the planting machine from one type of seeds to another. Firstly, the difference in the sizes of different seeds (i.e., corn vs. soybeans) present a problem in that a given sensing arrangement having a given fixed sensitivity for the purpose of sensing a relatively large seed (e.g. corn) may fail to respond reliably to a substantially smaller seed (e.g., soybean). Secondly, the rate of planting may differ substantially for different types of seeds, such that a sensor having sufficient sensitivity for a given relatively slow rate of planting (e.g., of corn) may fail to respond rapidly enough to count all of the seeds planted at a substantially higher rate of planting (e.g., soybeans). Thirdly, the attitude of seeds at the point of detection by the sensor may differ substantially when different types of seeds are being planted. In addition to the foregoing problems, both the rates of planting and attitudes of seeds may also differ as between seed planting machines of different makes and models or configurations.
With particular reference to the problems encountered when switching over from planting corn to planting soybeans, it should be noted that soybeans are substantially smaller than kernels of corn and moreover that typical planting rates for soybeans tend to be significantly higher than those for corn. Accordingly, a soybean passing a seed sensing device will not only be considerably smaller than a corn kernel, but will also be followed more closely by additional soybeans. Consequently, the sensing and counting of soybeans place a considerably greater demand, in terms of both sensitivity of response and accuracy, upon the sensor and associated monitoring apparatus than do the sensing and counting of corn. Additionally, a problem has heretofor been encountered in obtaining adequate "coverage" of the entire path of travel without unduly narrowing the path of travel which may cause clogging, particularly at the high rate of planting of soybeans. However, it will be recognized that attempts to use two or more photosensitive devices to "cover" the path of travel may result in erroneous counts of the seeds because a single seed may trigger a response from both photo-sensitive elements.